In the communications industry, particularly the telephone industry, there is often a need to electrically connect a relatively large number of circuits or leads with other circuits or leads. This is true both in initial installation of equipment, and as a result of growth, personnel relocation or reassignment, change of telephone numbers, increased sophistication of telecommunications equipment and other factors. As a result, electrical connections between incoming communications leads and outgoing communications leads change on a regular basis.
To allow the frequent circuit changes which are required in this environment, it is conventional to provide circuit access items commonly referred to as connector panels or terminal blocks. These products provide termination of incoming and outgoing leads on one side of the terminal block or panel, while the other side of the terminal block or panel is used to make and change circuit connections between the leads.
On the side used to make and change connections between the leads, various types of electrical connector structures and methods have been used. In some cases, the electrical connector has been a conventional wire wrap pin with the connections between individual pins on the panel being made using a conventional wire wrap or soldering process. These systems have singnificant shortcomings because of the time-consuming and labor-intensive process of making and changing such connections.
As a result of such problems, a system of patch cords and patch plugs was developed for the front faces of panels to access particular circuits or leads merely by plugging in individual patch plugs into jacks mounted on the front of the block or panel. However, such a system was very expensive and required the keeping of a large inventory of different lengths of patch cords for the purpose of making desired connections.
Eventually, connectors were developed which eliminated the need for patch cord systems. These connectors provided a means for directly connecting one end of a connecting wire to a connector element on the front of a panel or block and the other end to a second connector element. Typically, the individual connectors were configured so that, with use of a simple tool, the connector wire could be stripped of insulation to make an electrical contact by means of a tool which forced the connecting wire end through an insulation displacement slot or groove sized to cut through the insulation. The two major types of insulation displacement contacts available which have been commercially successful are split beam and split cylinder contacts. An example of a split cylinder contact is shown in application Ser. No. 650,252 filed on Sept. 13, 1984, which is a continuation of application Ser. No. 321,107 filed on Nov. 13, 1981 and assigned to the assignee of the present application.
The split beam and split cylinder connectors have been a significant improvement over the earlier connectors used in terminal blocks and access panels. However, there has long been a need for improvement in these connectors. First, because of the forces involved, and the relative rigidity of a traditional split cylinder insulation displacement connector element, there tends to be an undesirable force level on the conductor after termination is complete. A relative initial high force is desirable so that the insulation may be severed when the connecting wire is first inserted into the insulation displacement slot of the connector. However, once that process is complete, it is desirable to have a lower force on the wire to maintain the electrical connection. Higher forces in this area tend to increase the risk of wire fatigue and breakage.
In addition, it is desirable to be able to terminate more than one wire, or wires of different gauges, on these contacts. Different installers, or the same installer at different times may use different wire gauges, and a traditional split cylinder connector does not readily handle different wire gauges with adequate connection reliability and performance.
It is also desirable to have an insulation displacement connector which will handle strand-type connector wire without cutting through a high proportion of individual wire strands. This requires a relatively low final connection force between the connector element and the connecting wire.